Biological Oceanography

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In 1887 Hensen (Germany) first introduced the term plankton. The word “plankton” is derived from the
Greek word “planktos” meaning “wandering”. According to Hensen “They are tiny microscopic aquatic
organisms including both plant and animals having limited capacity to move but which have insufficient
power for keeping themselves or preventing themselves against water currents,tide and wind etc.
Plankton is a community including both plants and animals that consists of all those organisms whose
powers of locomotion are insufficient to prevent them from being passively transported by physical
factors. It may be defined as floating or drifting organism which has limited power of locomotion or
movements.
Size categories
There is no single agreed classification of plankton by size and the student will find the same terms
applied to slightly different size categories in older texts. The definitions given below are based on those
given in Omori and Ikeda (1984) which are both practical and easy to understand.
1. Megaloplankton – Gelatinous plankton such as medusae (jellyfish) and salps, 20 mm.
2. Micronekton – These fall into the same size category as megaloplankton but the term is usually
applied to strongly swimming animals such as euphausids, mysids and fish larvae, 20–200 mm.
3. Macroplankton – Large planktonts visible to the unaided eye,such as pteropods, copepods,
euphausiids and chaetognaths, 2–20 mm.
4. Mesoplankton – The principal components of zooplankton fall into this and the
5. macroplankton category. Mesoplankton includes cladocerans,copepods, and larvaceans,200 m–2
mm.
6. Net plankton – The four larger size categories described above are collectively called net
plankton because they can be effectively caught using nets.
7. Microplankton – Includes most phytoplankton species, foraminiferans, ciliates, rotifers and
copepod nauplii, 20–200 m.
8. 8. Nanoplankton – Organisms such as fungi, small flagellates and small diatoms, 2–20 m.
9. Ultraplankton or picoplankton – Mainly bacteria and cyanobacteria, 2 m.
Water bottle plankton – The three smaller categories (micro-, nano- and ultraplankton) which cannot
effectively be caught by nets.
Habitat categories
1. Epiplankton – Plankton of the epipelagic zone, i.e. within the uppermost 200 m.
2. Pleuston – Passively floating organisms living at the air–sea interface,partially exposed to air and
moved mainly by the wind (Cheng, 1975).
3. Neuston – Small swimming organisms inhabiting the surface water film, epineuston on the aerial
side, hyponeuston on the aquatic side.
4. Bathyplankton – Plankton of deep levels.
5. Hypoplankton – Plankton living near the bottom.
6. Protoplankton – Pelagic bacteria and unicellular plants and animals.
7. Seston – Finely particulate suspended matter.
General characteristics of Plankton:
1: Planktons are aquatic organisms with limited or no locomotors powers, involuntarily
independent of the shore and bottom or remain suspended in the water column.

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2: Planktons are organisms either plant or animals, relatively small and microscopic.
3: Their distribution is affected by water motion, waves and currents.
4: Plankton is at the base of the food web.
5: Plankton includes much different photosynthetic and chemosynthetic specie.
Adaptations of plankton
Adaptation, in biology, process by which an animal or plant species becomes fitted to its
environment; it is the result of natural selection’s acting upon heritable variation. Even the simpler
organisms must be adapted in a great variety of ways: in their structure, physiology, and genetics,
in their locomotion or dispersal, in their means of defense and attack, in their reproduction and
development, and in other respects.
Adaptations can take many forms: a behavior that allows better evasion of predators, a protein that
functions better at body temperature, or an anatomical feature that allows the organism to access
a valuable new resource — all of these might be adaptations.
Surface area and volume
● All phytoplankton and many zooplankton are microscopic in size.
● Their small size and complex shapes produce a high surface area-to-volume ratio.
● A high surface area-to-volume ratio favors the rapid exchange of gases by diffusion and creates
a high frictional resistance, which means they sink slowly.
● It also facilitates the rapid excretion of wastes across the body surface, light trapping, and
nutrient absorption.
Increased buoyancy
● Many plankton have buoyancy aids.
For example, phytoplankton, notably diatoms, and zooplankton such as copepods, fish eggs, and
larvae, contain bouyant oil droplets that also act as food stores.
● Some planktonic cyanobacteria and radiolaria contain gas-filled vesicles.
● Certain dinoflagellates, and various zooplankton, including salps and comb jellies, exclude or
excrete heavy ions (e.g., Mg2+, SO42–) and retain less dense ones (e.g., NH4+, Cl–).
Body shape
● Many plankton have body shapes that tend to make them sink more slowly.
● Some plankton are flattened. They sink slowly, moving back-and-forth in a “falling-leaf ”
pattern.

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● Long projections and spines increase surface area and slow sinking. They may also deter
potential grazers or predators from consuming the individual.
● Chains of individuals can assume shapes that encourage sinking in a slow spiral or zigzag path.
Seasonal abundance of plankton in BAY OF BENGAL
Phytoplankton is one of the biological components that initiate the marine food chain by
serving as food to primary consumers like zooplankton, fish etc., 1. The marine ecologists
have used biotic and abiotic factors in the structuring phytoplankton community operating
on a relatively local scale2. The diverse forms and size of phytoplankton play important
ecological role in the ecosystem3. Phytoplankton abundance and composition of an aquatic
ecosystem are governed by various physico-chemical factors.
North-east wind blowing season(Nov – Feb):
This season is characterized by –
# Wind blowing occurs mostly North - Easterly.
# Rainfall is low.
# Salinity is higher due to low rainfall and ranger between (20 – 25) ppt.
# Transparency is higher in absence of rainfall as well as raises discharge and turbidity range (10
– 45) cm.
# Water temperature between (22 – 28)o C.
# Surface water gets cool. Conventional and wind mixing extends deep into
water column bringing a lot of nutrient to the surface.
Organism: -
1. Although the temperature and light intensity is low, the nutrient level is
very high and salinity transparency is favorable. Some species of
phytoplankton are usually occur here mainly included the decision of
Bacillarophyta, Cynophyta, Chlorophyta.
2. Among them the Bacillarophyta is dominant which consist about 80 % of
the phytoplankton species. During this time the peak is found in January
(2100 cell/L) because in this time the amount of rainfall is negligible and
transparency is high.
Pre-monsoon (March – April) spring:
It is characterized by –

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# Rainfall is moderate.
# Salinity is higher due to low fresh water discharge (20 25) ppt
# Transparency decreased (35 – 40) cm.
# Water temperature between (27 – 30) oC.
Organism: -
During this time, the plankton communities are decreased due to less
transparency of water and also for nutritional lackage.
Monsoon (May – August):
This season characterized by –
# Wind blowing South – easterly.
# Heavy rainfall occurs caused by wind blowing (30 – 70) cm.
# Salinity is lower due to heavy fresh water discharge (8 – 20) ppt.
# Transparency decreases due to turbidity of water.
# Surface water becomes warm.
Organism: -
1. During this season low concentration of phytoplankton is found due to negative effect of
rainfall, which reduces salinity and temperature.
2. In the month of June when highest rainfall occur and salinity decreases rapidly then occurs
minimum concentration of phytoplankton and this concentration is about 600 cell/L.
Post Monsoon (Sep – Oct):
This season is characterized by –
# Rainfall is moderate, i.e. decreasing gradually (50 – 20) cm.
# Surface water becomes cool.
# Water transparency is increasing.
# Surface water is rich in nutrient content.
Organism: -
1. As the enriched nutrient level become unused during the monsoon, a rapid growth of
phytoplankton occur specially composed of Skeletonema, Biddulphia, Coscinodoscus etc, due to
favourable combination of temperature, light, nutrient supply and stable water column.

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2. During this time specially September, Bacillarophyta reaches sits peak concentration such as
1300 cell/L and October is about 2900 cell/L.
Phytoplankton
The term phytoplankton is derived from the Greek word “phython” meaning “plant”.
Phytoplankton is microscopic, drifting and chlorophyll bearing autotrophic organisms whose
movement from one place to another place due to water current. Marine phytoplankton is made up
small plants, mostly microscopic in size and unicellular. The phytoplankton often also includes a
numerous and diverse collection of extremely small, motile plants collectively terms micro
flagellates.
Importance of phytoplankton:
Merits:-
1. Phytoplankton performs photosynthetic process through which organic food is produced for
animals.
2. They occur at the base level of food chain and food web.
3. Phytoplankton makes balance the organic environment by releasing O2 and taking CO2.
4. Primary production depends upon phytoplankton.
5. Some organic matters and soil obtain from phytoplankton.
6. Phytoplankton is used as insulator to prepare bombs.
Demerits:-
1. Formation of water bloom.
2. Formation of red tide which is harmful for animals.
3. Dynamite is made of phytoplankton.
4. Excretion of toxic materials
Classification of phytoplankton:
On the basis of size, structure, body shape, chromatophore patterns and nutritional value,
phytoplankton are classified into three types –
A) Diatom
B) Dinoflagellates
C) Nanoplankton
There are at least eight major types of phytoplankton, of which the most important are the
diatoms and dinoflagellates.In the past decade,the small coccolit phores and silicoflagellates and

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the extremely small autotrophic pleoplankton, has been found to the more important in world
productivity than most researchers could have imagined.
A) Diatoms: -
*The majority of the diatoms are unicellular, uninucleate plants with a size range of about 15 µm
to 400 µm in maximum dimension, although some smaller and a few considerably larger formes
exists.
1. The diatom cell known as frustules, consist of silica (SiO2).
2. Fully 55% of energy of sunlight absorbed by a diatom.
3. It contains chlorophyll a and c and accessory pigment xanthophylls.
4. Diatom store energy as fatty acids and oils.
5. Reproduction is asexual and bisexual.
6. More than 5600 species of diatoms are known to exist.
7. Most are round, but some are elongated or branched or triangular.
8. Diatoms reproduction by cell division and auxospore formation.
9. Diatom means ‘‘To cut through’’. (Dia = Through, toms=to cut)
Importance of zooplankton:-
Merits:-
1. By using as food, zooplankton balance the topic level of the food chain and food wed.
2. Zooplankton is used in fish hatcheries as food.
3. Dead zooplankton become decomposed and release CO2 which is essential for photosynthesis.
4. Some zooplankton is eaten by people.
5. Zooplankton especially copepods are used as indicator species.
Demerits:-
1. Zooplankton increases the amount of CO2 where photosynthesis does not occur.
2. Some zooplankton contains poison which is harmful for other other organisms.
Factors
Physical factors:
1. Light: -
Generally we can say that directly or indirectly light control the grpwth and distribution of the
major marine life and it is the most important ecological factors in the sea. The availability of the

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sunlight as the source of radient energy is an essential factor of production and growth of
phytoplankton.
*Photosynthesis: Photosynthesis is the basic need of phytoplankton take place
in the euphotic zone.
Sunlight
nCO2_+ nH2O (CH2O)n + nO2
Chlorophyll
*Compensation: -
The depth of which the rate of production of organic material by photosynthesis escacity balance
the rate of break down of organic material by plant respiration is called compensation depth (Pc
= Rc). Below compensation depth there is not net production. (Pc < Rc)
2. Temperature: -
Temperature is a significant factor because any changes in temperature may affect on the growth
of phytoplankton. Some important affect are as follows – Temperature is related to salinity,
circulation, CO2 .Because of huge temperature the mass of water is occurred in the ocean.
*Phytoplankton Culture: -Growth rate of phytoplankton culture largely depends on
temperature.For this need (18-20)o C temperature.
*Respiration: -Respiration rate also increase or decreases with the changes of temperature.
*Metabolism: -The rate of metabolism is much accurate with the rise in temperature.
*Flotation: -Flotation of phytoplankton depends upon necessity of water which controlled by
Temperature.
*Solubility: - Solubility of O2 also decrease with the increase of temperature. The differences
In dissolved O2 content, may prove limiting phytoplankton growth.
3. Hydrostatic pressure: - The pressure increase with the increase of depth. At the lower part of
water. Plankton die due to high pressure. It has direct effect on protoplasm and increase the
viscosity hence it influence the growth and reproduction of phytoplankton.
4. Salinity: - Salinity is the important factor for phytoplankton growth. Salinity maintains the
osmotic relationship between the protoplasm and surrounding water. Excess or low salinity
causes mortality. Some diatoms of neritic form have a wide range of salinity tolerance and
known as Euryhaline that is capable of extending. Only small changes in salinity.
5. Specific gravity: -We know that specific gravity α 1/Temp and specific gravity α salinity.
*Temperature and salinity control the specific gravity.

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*So reproduction, growth, abundance and distribution of phytoplankton are indirectly affected by
specific gravity.
6. Turbidity: - It is a complex and irregular movement of ocean water. It may increase present
production by enriching nutrient to the surface water, but in very turbid water that contain a large
quality of suspended particle sufficient light cannot penetrate.
Chemical factors:
1. Oxygen (O2): -
*It is essential for biotic organisms in respiration.
*Respiration of phytoplankton cannot go without the supply of O2. Lack of O2 means the death
of phytoplankton.
*Excess or low O2 content of water is harmful for growth of phytoplankton.
*It is necessary for breakdown of food.
2. Carbon-di-oxide (CO2):-
*CO2 is an important ecological factor which limits the growth of phytoplankton.
*Except CO2, phytoplankton cannot manufacture their food.
3. pH or (Hydrogen ion concentration): -
*The pH range of sea water is normally about 7.5 – 8.5.
*The increase or decreasing of pH directly affects on phytoplankton growth.
4. H2S: -
*Created by bacterial decomposition of organic substances.
*It has destructive effect on phytoplankton growth.
5. Nutrients: - [2008]
*It plays most important role in the biological process of sea water.
*PO4 and NO3 are very important for protein synthesis in phytoplankton.
*If nutrition is decrease the primary production is decrease.
Dynamic factors
1. Current: -
*This is an important factor which influences the distribution of phytoplankton.
*It may disperse spores, eggs, adults to a suitable place for survival or may
negative effect by carrying them to unfavourable place.

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2. Tide: -
*A lot of phytoplankton die when trapped in cast during high tide.
*By increasing turbidity in coastal region, tide hampers the primary productivity.
3. Wave: -*A lot of phytoplankton comes to the coast by waves and ultimately they die.
*It is destructive factor for phytoplankton.
4. Turbulence: - *It is complex, irregular movement of water by which different layers of water
Mixed vertical. It may promote productivity by bringing nutrient to the surface.
*Long time effect of turbulence may be harmful for growth of phytoplankton.
5. Upwelling: -
*It brings nutrient rich water to the surface and increases the phytoplankton growth.
*The vertical circulation is also important for maintaining aerobic condition in the deep sea, H2S
is formed at the bottom due to lack of dissolved oxygen. E.g. Black Sea.
Biotic factors
1. Dissolved organic matter: -
*It has direct effect on primary production. By decomposing of plant and animals dead body,
organic matters discharge into sea and help the phytoplankton growth by giving NO3 and PO4.
*On the other hand it is the important nutrient media for heterotrophic bacteria, yeast, fungi etc.
Hence organic substance is necessary for the phytoplankton growth and other physiological
activities.
2. Grazing: -
*An important biological factor which limits the growth of phytoplankton.
*It has been found that with the increase of growth of phytoplankton, zooplankton migrate there
and graze on standing crops. Copepods and Mysid are very important grazer which easily migrate
to the area of heavy phytoplankton. Hence grazing is an important factor for phytoplankton growth
and abundance.
3. Competition: -
*In nature there are always inter species struggle strongly for food, space, light
and dominancy. In this striggle the fittest are only survive and other abolish.
*So the competition has an effect on growth and abundance acting as a regular.
4. Seston: -
Suspended particles are present in the sea water. Collectively known as seston.

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It absorbed light from the euphotic zone, reduces the depth of the
photosynthentic zone and also the conpensation depth. So it is very harmful for
Phytoplankton growth.
5. Food: -
*Food is the key factor for the living organism. The food of marine plankton is mainly inorganic
salt of CO2.Aquatic organism obtain a large part of their food, requirement from dissolved organic
matter. So sufficient quantities of food effect on the growth of phytoplankton.
6. Bioluminescence: -
*The light productivity phenomenon of various marine organisms is known as bioluminescence.
The light producing animals; include bacteria, Jelly fish, radiolarians, dinoflagellates, hydroids
and many fish species.
*For grazing purpose the herbivorous and carnivorous become as bioluminescence at night. So it
an essential and affective factors for the abundance growth and the development of phytoplankton.
7. Parasitism: -
*Different types of parasitic actively destroy the phytoplankton community and they also limit the
growth of phytoplankton.
*The above factors are most important for growth and developments of phytoplankton. There are
also some factors that affects that affect little on phytoplankton production and growth.
Secondary productivity: -
Secondary productivity is the rate which energy is stored in the consumer and decomposer tropic
level.
Causes of productivity measure:
a. It is often necessary for ecological to know the rate of production given environment.
b. By measuring productivity we are able to know the total amount of organic matter formed.
During photosynthesis or utilization or of other constituents necessary to photosynthesis.
c. To get calories volume of per square meter of surface per day or per year.
d. It is the index of fertility of the sea.
e. Productivity measurement produce/ information on the fishery.
Culture techniques of commercially important zooplankters - Artemia, Rotifer, Copepod.
Artemia
Artemia:

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Artemia is a small crustacean popularly known as -shrimp. This zooplankton naturally occurs in
salt lakes (coastal or inland chloride sulphate or carbonate rich waters). It is only occurring in the
evaporation pond if intermediate salinity levels i.e. – from about 100 ppt upto 250 ppt. The most
peculiar nature of this animal is that the embryos inside the cyst remain in diapauses as long as the
cysts are kept dry or under anaerobic conditions. It is omnivorous in food habit. Its food consists
for example of yeast, diatom, algae, bacteria and other microorganisms.
Systematic position:
Phylum – Arthropoda
Class – Crustacea
Sub-class – Branchiopoda
Order – Anostraca
Family – Artemiidae
Genus – Artemia.
Ecology:-
*Artemia are found in lakes e.g-Great salt lake, Utah and Chaplin lake Canada and brines pond
e.g – San-Francisco bay, California salt ponds.
*In these areas ecological conditions are extreme.
*Salinity can vary from 60 ppt to 300 ppt.
*Predators and food competitors are mostly eliminated.
Some species of Artemia with their locations:
Six species of Artemia with their location:-
1. Artemia salina.(England-Now extract)
2. Artemia tunisiana.(Europe)
3. Artemia fransiscana.(America)
4. Artemia monica.(Mono lake-california)
5. Artemia persimilis(Argentina)
6. Artemia urmiana.(Iran)
General distribution of Artemia: -
*So far over 300 natural Artemia- biotopes, spread over the 5 continents have been identified.
*The distribution of Artemia is limited to biotopes where salinity always is sufficiently high to
keep out predators.

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Wind and water-birds (especially flamingoes) are considered to be important natural dispersion
vectors.
Describe the life cycle of Artemia: -
Artemia undergoes various stages in its life cycle –
1. Cysts: -
a. The dehydrated dormant eggs of Artemia are called cysts.
b. They are 200 – 300 µm in diameter and appear as minute brown particle, weight may 3.5 µm in
average.
c. In dry and oxygen free conditions, they remain inactive.
d. Upon immersion in sea water (5 – 70) ppt, the bean shaped becomes spherical or hydrated and
within the shell the metabolism of the embryo is activated.
e. Few hours later, the cysts outer membrane.
2. Nauplii: -
a. A short period after the emerging of embryo, the hatching membrane raptures and the free
swimming Nauplius (about .4-.52mm).0.002-0.003 mg dry is released.
b. The first instars larvae are brownish orange due to the presence of yolk.
3. Juveniles: -
a. The larvae grow and differentiate through about 15 molts.
b. The trunk and abdomen elongate.
c. The digestive tracks become functional.
d. Lateral complex eyes developed.
4. Adults: -
*From the 10th instars on artemae undergo sexual differentiations.
*Adult Artemia usually 8-10mm long.
*Adult Artemia are characterized by –
1. Stalked lateral eyes.
2. Sensorial antennules.
3. Linear digestive track.
4.11 pairs of thoracopods.
5. In, male antenna is transformed into muscular gasper.

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6. A paired penis is found in the posterior part of the trunk region. IN femaleairtime have
degenerated into sensory appendages
7. Paired ovaries are found in both sides of the digestive track behind the thoracopods.
Riding Pairs: -
a. Precopulation starts with the male grasping the female with its Artemae
between the uterus and last pair of thoracopods.
b. The couples can swim around in this position for several days.
c. Copulation is very fast.
Discuss about the mode of reproduction of Artemia:
Two modes of reproduction exists in Artemia –
1. Oviparous reproduction and
2. Ovoviviparous reproduction.
1. Oviparous reproduction: -
a. In oviparous reproduction, after copulation fertilized eggs are surrounded by in the broad pouch
of the female with a tough brown sell, which is then called cysts.
b. It is predominant at high salinities (150-200) ppt and lower dissolved oxygen concentration.
c. The cysts are released by female in water where they will not hatch until they have completely
dehydrated.
d. The embryo inside each cyst is then in a state of metabolic dormancy and will not further
developing until hydrated again.
e. at these conditions, more hemoglobin is synthesized which may account for greater cyst
formation.
f. In nature, this mostly happens when pond water washed back after rainfall.
2. Ovoviviparous: -
*In ovoviviparous reproduction, after fertilization instead of surrounding by a shell eggs are
immediately developed i8nto nauplii in the broad pouch of the female.
*These nauplii are then released in water as free-swimming nauplii
*In this reproductive cycle, a female can produce 50-200 nauplii from anew batch of eggs in every
5 days.
Write down the feeding habits and food of Artemia.
Feeding habits: -

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a. Artemia is a non-selective filter-feeding animal that ingest anything in the size range 1 to about
50 microns.
b. It is omnivorous in food habit.
c. This animal feed on particulate organic detritus matter as well as living organisms of appropriate
size.
Foods: -
Its food consists of –
a. Yeast
b. Diatom, (eg-Nitzchia,Closterium,Sigma etc); Navicula, Blue green algae,
Euglena etc.
c. Green algae,eg-seenedesmus, quadricanola, Ankistrodesmus, pseudomicrobiles,
Amkistrodesmus arwatus, Crucigenia Caudrata, Cladophora sp, Dunaliella salina, Stephanaptera
gracitis, Stephanoptera oracillus etc.
d. Besides in cultured condition, Artemia can be feed directly with-
1. Chicken feed.
2. Rice bran.
3. Mineed fish.
4. Chopped chicken dung etc.
Prospects/possibility/potential of Artemia culture:-
Bangladesh has no naturally occurring Artemia. There is a great possibility of Artemia culture as
a byproduct of salt production in the coastal salt-pans of Bangladesh. Potentials of Artemia culture
in the coastal salt-pans of Bangladesh are given below –
*Favourable environmental conditions do occur at least during the post and premonsoon
season(Nov-March).In this day season salinity is being high which
may be suitable for culture of Artemia.
*Bangladesh has about 17000 hact. Of salt producing area and if one tenth of this area is modified
for integrated Artemia culture. Then the country would produce at least 48000 kg DW cyst/year
and 3600 tons WW biomass/year.
*Foods of Artemia are available here.
*Coastal aquaculture is developing rapidly in our country and there need a lot of food materials
for hatchery. So, the production of Artemia cysts and biomass in the salt pans is required to rear-
up these hatchery fry.

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*Geographical location of the saltpans of Baskhali, Chakaria, Coax’s bazaar,
Kutubdia, Maheshkhali Island is most suitable for Artemia culture.
Problems of Artemia culture: -
The possible culture problems of Artemia culture in Bangladesh are given below-
1. The people who live in the coastal area are poor and illiterate. So, they do not like to take any
risk of Artemia culture in their saltpans
2. People of coastal are poor, so they cannot bear the primary cost for Artemia culture.
3. In rainy season, it is not possible to grow Artemia for heavy rainfall.
4. In Bangladesh, we have no naturally occurring Artemia cysts. So, we have to import Artemia
cysts from foreign countries.
5. Salinity varies in the coastal area of Bangladesh. If salinity is > 70% and <
5%; then Artemia culture is hampered.
6. In summer season, the temperature is very high. So, Artemia cysts may die due to high
temperature.
7. Facilities are not available. There is no plan in government to develop
Artemia culture in the coastal salt pans of Bangladesh.
Uses and importance of Artemia:
The uses and importance of Artemia are given below –
* Artemia serves as an important food for early stages of shrimp and other organisms in aquarium
and small ponds having no natural foods.
* Being live food, the larvae of Artemia are readily taken by aquatic animals under nursery
conditions without fouling the aquarium water.
* Its constitute the principle ration and frequently the only food for larvae and juveniles of many
cultured species, such as – fresh water prawn (Macrobrachium sp), shrimps (Peneaus sp), lobster
(Homorus sp), crabs and various fishes.
* Problems in the salt making created by organic metabolites from algal blooms, can be
biologically controlled by the presence of brine shrimp, Artemia.
* The dark red coloration of Crystalizers, holobacterium is directly cow tat with Artemia presence
earlier in the system.
* It creates job opportunity for both technocrats and general people. Financially it is beneficial for
the poor salt farmers of the country.
* It earns foreign currency by exporting Artemia biomass to other country.

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Why Artemia sp. selected for culture?
Artemia sp. is selected for culture because of its outstanding characteristics which are as follows
–* Handover: It is convenient to handle since it can stay in the dormant stage as dry cysts which
can be easily stored, transported and hatched.
Adaptation: It is adaptable to a wide range of environmental condition.
Capacity: Artemia sp is a non-selective filter feeder and is capable of growing at very high
densities. [More than 10,000 individuals per liter].
Generation Time: Artemia sp also has an unchanging food requirement high conversion efficiency,
short generation time, high fecundity rate and considerably long time span. [up to 6 months or
more].
The culture techniques of Artemia Salina in the coastal salt-pans: Introduction:
Culture may be defined as man’s attempts to improve the yield of useful aquatic organisms by
deliberate manipulation of their rate of growth mortality
Production.
Now the culture o zooplankton like Artemia salina is described below –
Collection: -
Artemia are not found available in our country. For this reason cysts are imported from foreign
countries. In our country laboratory culture of Artemia has not yet been done.
Culture materials and methods:
1. Equipments and other inputs: -
a) Artemia cysts [e.g. – red jungle brand, USA]
b) One salt-pond. [1000 m2]
c) Equipments for monitoring water quality [pH, DO, S %o, temperature]
d) Equipments for collecting and clearing Artemia cysts.
e) Organic and inorganic fertilizer.
f) Equipments for dehydration of Artemia cysts.
2. Site selection: -
* The site should be selected in places with low rainfall and high evaporation rate.
* Dry season last from 4 to 6 months.
* The site may be selected in existing salt production ponds. 3. Pond preparation:
a. Modification of existing salt-pan: -

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* The Artemia production ponds (APP) are modified to hold more bring than the traditional ones.
* They are excavated in the 4th compartment.
* Water depth of APP is maintained to around 30 cm.
* Water temperature should not exceed (35-36)o C.
b. Construction of cysts barrier: -
* For better harvesting cysts barrier is required.
* At the dyke side of the APP, cysts barrier are fabricated with bamboo frame and with black
polythene sheet for collection cysts at case.
c. Limiting of the ponds: -
* To control the soil acidity lime is used.

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* Lime is applied at a rate of 20kg/acre.
d. Prevention against Lab-lab growth: -
* To prevent lab-lab growth the pond bottom is dried and racked up and all traces of decayed lab-
lab are removing.
e. Water intake: -
* Sea water of salinity 30%o is pumped in reservoir.
* The water is passed through a screen of 1mm mesh to prevent shell are fin fish larvae.
f. Fertilization: -
* After six days of water intake when salinity is 57 %o then pond water is
Fertilized as follows –
Inorganic fertilizer – 50 kg/hack
Organic fertilizer – Chicken manure may be applied at 2 ton/hac.
4. Treatment for Artemia cysts for inoculation:
a) Inoculation Time: -
* Artemia may be inoculated early in the morning, late in the afternoon or preferably early in the
evening.
b) Hatching: -
* 30 gm. of Artemia cyst and 3 liter of sea water (35 %o) are taken in a plastic container.
* After 30 hours the nauplii are hatched out.
c. Incubation: -
* Newly hatched nauplii are taken in a polythene bag.
* Concentrated sea water from APP is introduced slowly to help to adapt nauplii to the
temperature-salinity regime of the APP uniformly.
d. Water management: -
* Hydrological parameters of the APP are recorded at 5 days intervals following standard method
at the culture site.
* Water depth is maimed around 30 cm and water temperature is <35o C, salinity gradually
increased to as high as 153%o.
e. Observation and results: -
Air temperature – (22.5-33) o C

19. 19
Water temperature – (29-35) o C
Salinity – 50%o at beginning and maximum recorded 153%o in April.
Dissolved oxygen – (4-6) ml/L
Water depth – (24-30) cm
pH – (7.7-7.9)
5. Harvesting: -
* Whenever the cysts float on the surface of the pond water, they accumulate on the wind ward
side against the cysts barriers.
* Cysts are collected with a double screen dip net. The older screen is of 500 µm to remove adults
and the inner screen of 120 µm to retain cysts.
6. Cyst Processing: -
* Soon after collection, cysts are put on a sieve and washed with several changes of fresh water to
remove larger particles if present.
* The cysts are then transferred to a container filled with water of 250-300. Aeration is provided
continuously from a tube.
* Cysts are then removed from the container and allowed to be dried in the air avoiding direct
sunlight.
* The dried cysts are transferred to screw capped containers and kept in cool and dry place.
Conclusion: -
Artemia has manifold importance. By culturing Artemia we can fill up the scarcity of food supply
in our aquaculture firm easily. Artemia is also a good food for shrimps. We can develop our shrimp
production by the culture of Artemia. So, culture of Artemia should be extended in the coastal salt-
pans of Bangladesh.
Problems of Artemia culture:
Technical problems are as follows –
a) Lack of cyst collection and production.
b) Lack of culture practice.
c) Lack of the planning of the culture farm.
d) Lack of the basic knowledge on the biology and habit of Artemia to be cultured.
Major factors to be considered for culture of Artemia
salina in coastal pond/ saltpans:

20. 20
The factors which are considered for culture of Artemia salina in the coastal pond/ saltpans are as
follows –
1. Salinity – 50 ppt at beginning and maximum record 153 ppt in April.
2. Water temperature – (29-35)O C.
3. Dissolved O2 – (4-6) ml/L.
4. Water depth – (24-30) cm.
5. pH – (7.7-7.9)
Red Tide
Sometimes the abundance of phytoplankton in the sea water becomes so greater as to discolor the
water to reddish or yellowish blue. Some occurrence of reddish Colour in water body also
associated with dinoflagellates is termed as red tide.
Or, Discoloration of surface seawater owing to high concentration of microscopic organisms
(especially dinoflagellates) is called the red tide. Actually red tide is
a –1. Reddish brown discoloration of surface water.
2. Usually takes place in coastal areas.
3. Caused by high concentration of microscopic organisms usually dinoflagellates. If
dinoflagellates extremely abundant (2-8 million/L) the cumulative effect of all the toxics released
such extreme concentration or bloom of dinoflagellates causes red tide. It is responsible for the
massive mortality of organisms especially fish and invertebrates.
The organisms associated with red tide belong to three main groups. They are –
i. Diatoms
ii. Dinoflagellates: Gymonodinium brevis, Gonyavl tamarensis,Noctiluca miliaris etc.
iii. Blue green - algae: Trichodesmium
In estuaries and tropical waters blue-green Trichodesmium sp. is responsible for red tide. In
temperate waters, dinoflagellates responsible include Noctilvca miliaris, Gonyavlax sp etc.
Effect of red tide: -
1. Toxins produce by dinoflagellates may kill fish directly.
2. The fishes of red tide regions are toxic. These fishes are suitable for man’s food.
3. When men take red tide regions water, they can have vomiting. Even if men bathe in the
red tide waters, they may suffer skin diseases.
4. The over blooming organisms of red tide region may use up the O2 in the surface water to
cause suffocation of many animals.

21. 21
Control of red tide: -
1. Introduction of vit-B12 destroying bacteria.
2. Encouragement of nature predators that eat phytoplankton.
3. Copper poisons to control the production of red tides.
Not all red tide are toxic. Nocticula a dinoflagellates may turn the sea water Colour of tomato soup,
but it is not toxic. The red sea and Gulf of California at times get their red Colour from certain
species of blue-green algae (Trichodesmium sp.) which is not toxic.
Diurnal migration:
Migration may be define as the periodic movement of an organism from one place to another is a
particular season or time for various purpose such as feeding, breeding, avoidance adverse
condition and also for survival aspect. In aquatic environment, it is the movement of fish or any
other invertebrates and vertebrates from feeding ground to spawning ground or back again from
nursery ground to feeding ground and from spawning ground to nursery ground. The migration
which occurs during day-night is called diurnal migration. Many planktons in both marine and
fresh water situation make more or less extensive diurnal migration. Such migration may be
towards the surface at night when temperature is low and twilight present and down into the depth
at day time when the light is excess. Some this migration is reverse of this with towards the surface,
at day time and back to the depth at night.
Causes of diurnal migration: -
Aber of attempts has been made to explain the stimulus that regulates diurnal Migrations. The
most important of these are –
1. Phototropism
2. Interaction of phototropism and geotropism.
3. Temperature change
4. Hunger
5. Physiological rhythm.
Merits: -
1. It provides the elimination of gross and net production and respiration at a time.
2. Required instruments and reagents are available, inexpensive and convenient in handling
Demerits: -
1. If water samples enclosed in bottles for period, the results can very.

22. 22
2. This method has limitation to high production rates exceeding about 50 mgc/m2/day.
Precaution: -
The O2 concentration of initial bottle is measured as quickly as possible.
Coral reef
Coral reefs are diverse underwater ecosystems held together by calcium carbonate structures
secreted by corals. Coral reefs are built by colonies of tiny animals found in marine waters that
contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps
that cluster in groups. The polyps belong to a group of animals known as Cnidaria, which also
includes sea anemones and jellyfish. Unlike sea anemones, corals secrete hard carbonate
exoskeletons which support and protect the coral polyps. Reefs grow best in warm, shallow, clear,
sunny and agitated waters. Often called “rainforests of the sea”, shallow coral reefs form some of
the most diverse ecosystems on Earth. They occupy less than 0.1% of the world’s ocean surface,
about half the area of France, yet they provide a home for at least 25% of all marine species,]
including fish, mollusks, worms, crustaceans, echinoderms, sponges, tunicates and other
cnidarians. Paradoxically, coral reefs flourish even though they are surrounded by ocean waters
that provide few nutrients. They are most commonly found at shallow depths in tropical waters,
but deep water and cold water corals also exist on smaller scales in other areas. Coral reefs deliver
ecosystem services to tourism, fisheries and shoreline protection. The annual global economic
value of coral reefs is estimated between US$29.8- 375 billion. However, coral reefs are fragile
ecosystems, partly because they are very sensitive to water temperature. They are under threat
from climate change, oceanic acidification, blast fishing, cyanide fishing for aquarium fish,
sunscreen use, overuse of reef resources,and harmful land-use practices, including urban and
agricultural runoff and water pollution, which can harm reefs by encouraging excess algal growth.
Coral in Bangladesh
The offshore island of St. Martin’s is the only area with corals in Bangladesh and is heavily
influenced by monsoons and frequent cyclones. Coral communities extend to about 200m offshore
of St. Martin’s Island with maximum coral cover of 7.6% and colony density of 1.3m-2. These
comprise 66 hard coral species, the most common are Porites, Acropora, Favites, Goniopora,
Cyphastrea and Goniastrea. Acropora spp. are the target for coral harvesters, as well as Favites
and Goniastrea. There are also many soft corals, sea fans, and sea whips. Other invertebrates are
only represented by a few, with molluscs being the most abundant large invertebrates, however,
these are declining due to unregulated harvesting. The major threats to the coral habitats are high
levels of sedimentation, cyclones, storm surges, freshwater and agricultural runoff, pollution from
human settlements and the removal of coastal vegetation. There is also over-harvesting of corals,
sea cucumbers and molluscs by excessive numbers of subsistence fishers. The removal of
Acropora and other coral colonies for the curio trade is also a major threat to the reefs, such that
Acropora are now rare.
What is Coral?

23. 23
Corals are composed of thin plates, or layers, of calcium carbonate secreted over time by hundreds
of soft bodied animals called coral polyps. Polyps range in size from a pinhead to a foot in length.
Each polyp lives in a symbiotic relationship with a host zooxanthellae that gives the coral its color.
Zooxanthellae take in carbon dioxide, process it through photosynthesis, and give off oxygen and
other important nutrients that are then used by the host polyp. As in all photosynthesizing
organisms, this means that corals must be exposed to a sufficient amount of sunlight. This confines
most corals to shallow waters that are clean and clear.There are two kinds of corals: hard and soft.
Hard corals (Scleractinia), such as brain, star, staghorn, elkhorn and pillar corals have rigid
exoskeletons, or corallites, that protect their soft delicate bodies. Soft corals (Gorgonians), such as
sea fans, sea whips, and sea rods, sway with the currents and lack an exoskeleton.
Coral bleaching
Bleaching occurs when the conditions necessary to sustain the coral’s zooxanthellae cannot be
maintained. Any environmental trigger that affects the coral’s ability to supply the zooxanthellae
with nutrients for photosynthesis (carbon dioxide, ammonium) will lead to expulsion. This process
is a “downward spiral”, whereby the coral’s failure to prevent the division of zooxanthellae leads
to ever-greater amounts of the photosynthesis-derived carbon to be diverted into the algae rather
than the coral. This makes the energy balance required for the coral to continue sustaining its algae
more fragile, and hence the coral loses the ability to maintain its parasitic control on its
zooxanthellae. Physiologically the lipid composition of the symbiont thylakoid membrane affects
their structural integrity when there is a change in temperature, which combined with increased
nitric acid results in damage to photosystem II. As a result of accumulated oxidative stress and the
damage to the thylakoid of chloroplasts there is an increase in degradation of the symbiosis and
the symbionts will eventually abandon their host. Not only does the change in temperature in the
water increase the chances of bleaching, but there are other factors that play a role. Other factors
include an increase in solar radiation (UV and visible light), regional weather conditions, and for
intertidal corals, exposure to cold winds.
Mangrove
The term “mangrove” is derived from two Portuguese and English words, “mangue” and “grove”,
respectively.
UNESCO defined: “The mangroves are the evergreen sclerophyllous, broad leafed trees with aerial
roots, like pneumatophores or still roots and viviparous germinated seedlings”
Hamilton and Snedaker (1984) defined: “The mangroves are salt tolerant forest ecosystem of the
tropical and subtropical inter-tidal regions of the world”
Characteristics of mangrove:
2. Mangrove is salt tolerance.
3. Grow well in shallow water and obstruct tidal currents.
4. They become established in coastal region at muddy land
5. they share more or less similar physiognomy.
6. The mangroves are generally flooded with brackish water during high tide.

24. 24
7. Many of the individuals’ species possess unique adaptation as prop-roots (rhizophora),
pneumatophores (Avicennia), salt gland, viviparous germination.
8. They have thick leaves. The lower side of the leaf has stem for limiting transformation.
9. They are some halophytic plants and some are xerophytic plants
10. Excellent soil builders.
11. Global overview of Mangrove forest:
12. Mangrove can be found in over 118 countries and territories in the tropical and subtropical regions of
the world. Mangroves are various types of trees up to medium height and shurbs that grow in saline
coastal sediment habitats in the tropics and subtropics- mainly between latitudes 25° N and 25°S
(159,572 Km2
. Total mangrove area is predominated by four countries: Indonesia (30,620 Km2
),
Australia (14,514 Km2
), Brazil (10,124 Km2
) and Indo-Bangladesh (10,228 Km2
). In total, these four
countries represent 41% of the world mangroves.
Table. Various estimates of mangroves areas, together with percentages of global totals (Km2
)
Region Mangrove area
FAO (2007)
Mangrove area
Spalding et al. (1997)
Mangrove area
IUCN (1983)
South and South-east Asia 60,208 (37.7) 75,173 (41.5) 51,766 (30.7)
Australia 20,185 (12.6) 18,789 (10.4) 16,980 (10.0)
West Africa 32,417 (20.4) 27.995 (15.5) 27,110 (16.0)
East Africa and the
Middle-East
2,803 (1.6) 10,024 (5.5) 5,508 (3.3)
Americas 43,959 (27.5) 49,096 (27.1) 67,446 (40.0)
TOTAL 159,572 181,077 168,810
Importance of mangrove:
Natural products and ecological services of mangrove:
Natural Products:
 Fuel industry:
I. Firewood
II. Charcoal
III. Alcohol
 Construction:
I. Timber for scaffolds and heavy construction.
II. Beams, poles, flooring, paneling, etc.
III. Boat building
IV. Dock piling.
V. Thatch, matting

25. 25
 Fishing:
I. Poles for fish traps
II. Fish attracting shelters
III. Fishing floats
IV. Fish poison
V. Tannins for net and line preservation
 Food and beverages:
I. Fish
II. Crustaceans
III. Molluscs
IV. Other fauna
V. Vegetables from propagates, fruit and leaves.
VI. Sweetmeats from propagates.
VII. Condiments from bark
VIII. Sugar
IX. Honey
X. Cooking oil.
XI. Tea substitutes.
XII. Alcohol
XIII. Vinegar
XIV. Fermented drinks
 Household items:
I. Furniture
II. Glue
III. Wax
IV. Household utensils.
V. Incense
VI. Matchsticks
 Textiles, leather:
I. Fur, skins
II. Synthetic fibers (e.g. rayon0
III. Dye for cloth
IV. Tannins for leather preservation
 Other products:
I. Fish, shellfish and mangrove roots for aquarium trade.
II. Madicines from bark, leaves, fruits and seeds.

26. 26
III. Fodder for cattle, goats, and camels.
IV. Fertilizers.
V. Lime
VI. Paper
VII. Raw material for handicraft.
VIII. Cigarette wrappers
Ecological Services:
1. Protection against floods, hurricanes and tidal waves
2. Control of shoreline and riverbank erosion
3. Biophysical support to other coastal ecosystems.
4. Provision of nursery, breeding and feeding grounds
5. Maintenance of biodiversity and genetic resourdes.
6. Storage and recycling of organic matter, nutrients and pollutants.
7. Export of organic matter and nutrient.
8. Biological regulation of ecosystem processes and functions
9. Biological maintenance of resilience
10.Production of oxygen
11.Sink for carbon dioxide
12.Water catchment and groundwater recharge
13.Top soil formation, maintenance of fertility.
14.Influence on local and global climate
15.Habitat for indigenous people.
16.Sustaining the livelihood of coastal communities.
17.Heritage values
18.Cultural, spiritual and religious values
19.Artistic values
20.Educational and scientific information
21.Recreation and tourism
Mangrove ecosystem:
The mangrove ecosystem is a very dynamic one, where changes are taking place regularly, and
within the range of mangrove habitats most major species grow within a given set of conditions.
Any major changes in these conditions may start to bring about changes in the growth pattern of
different species, a complete elimination of one or more species resulting from changes in the
composition of the forests, or in estreme cases, a complete disappearance of the forest. Because of

27. 27
this severe sensitivity to changes in habitat conditions, mangrove forests are very susceptible to
destruction.
An ideal Mangrove Ecosystem:
The mangroves or the mangals are dependent on the following inter-related environment and
geological factors, like Edaphic, geomorphologic, Geographical, Physical and Biological.
 Edaphic Factors: The physical, chemical and biological properties of the soil and water that
influence the living organisms of the mangrove.
 Geomorphologic factors: The factors governing the origin, formation and development of
the land in the inter-tidal zone where successively the living organisms grow and adapt.
 Geographical Factors: The position of the areas and relationship with the ambient water
supply, quality of water, nature and properties of soil, water and lte climatic factors.
 Physical Factors: nature and properties of the soil, mode of formation of the substratum
and also the overall climatic conditions of the environment.
 Biological factors: These factors play vital and significant roles in any ecosystem, as each
and every individual plant and animal species have intimate linkage, adaptation and
relationship with each other.